The presence of the Electrical Double Layer (EDL) near a solid-liquid interface results in the electrokinetic effect on pressure-driven liquid flow through microchannels. The equations governing the EDL field and the velocity field in the cross-section of rectangular microchannels are the two-dimensional Poisson-Boltzmann equation and the modified Navier-Stokes equation

respectively. In this paper

the equations are numerically solved employing a finite control volume scheme. The relationship between the pressure gradients and the Reynolds numbers is computed

and the differences between the predicted and the experimental Reynolds number from pressure gradients are well within 5%. It is found that the friction coefficients predicted by the model with electrokinetic effect are higher than that predicted by the macroscale fluid theory in the same microchannel. Stronger deviations are observed as the solution concentration decreases.